Lamp with variable intensity light source



April 28, 1959 R. Y. BOITEUX 8 LAMP WITH VARIABLE INTENSITY LIGHT SOURCE Fild April 3. 1956 !NVENTOR POLHNDYBOITEUX "a I. L BY ATTORNEY LAMP WITH VARIABLE INTENSITY LIGHT SOURCE Roland Y. Boiteux, Santiago, Chile Application April 3, 1956, Serial No. 575,752

4 Claims. (Cl. 240-81) This invention relates to an electric light of selectively variable intensity, and more particularly relates to such light wherein the intensity of the light emitted by the electric lamp thereof may be varied by altering the connections between the lamp and a transformer forming a part of the lighting device or fixture.

There is a wide need forv electric lights of variable intensity, either for greater comfort or for economy. For example, a group of people. frequently requires more light than one person alone in a room. Lights of variable intensity are also very useful in a double bedroom if one of the occupants gets up at night and does not Wish to wake the other. Further, sometimes it is desired to have a constantly burning night light; it would be desirable in many instances, to employ the same light both as a normal light and also as a night light.

Usuallythe desired reduction or variation in the inten sity of light emitted by a lighting device is obtained by use of a special lamp bulb containing several filaments, such bulb, in effect, being several lamp bulbs condensed into one. When one such filament burns out, the user must buy a new bulb, even though the other filament or filaments are intact, or continue to use the old bulb without the advantage of having the use of all the gradations of light intensity for which the lighting device was built. Sometimes the intensity of lighting of a lamp bulb is altered by use of a variable resistance in the supply circuit for the bulb. This is uneconomical, particularly for lower light intensities, because of the power lost in the resistance. Further, the heating of the resistance is undesirable.

The invention has among its objects the provision of an electric light of variable intensity which allows the use of an ordinary lamp bulb, which consumes very little cur rent when the voltage to which the lamp bulb is subjected is low, and which increases the total useful life of the lamp bulb very considerably. Further objects of the invention include the provision of an electric light of variable intensity which employs as an element thereof a variable voltage transformer in its supply circuit, and the provision of such light having a novel multi-position switch whereby the voltage impressed on the lamp bulb may readily be altered.

Still other objects of the invention include the provision of an electric light of variable intensity which is economically made and easily serviced, when necessary.

The above and further objects of the invention will be more readily apparent upon consideration of the following specification, and of the accompanying drawing, illustrating a preferred embodiment of a light in accordance with the invention, which forms a part of the specification.

In the drawing:

Fig. l is a view in elevation of the light or lighting device, the shade of the lighting device being omitted, portions of the shade holder being broken away and a portion of the wall of the base enclosure of the light being broken away,

i United States Patent Fig. 2 is a fragmentary view in axial section through the portion of the light at the variable voltage-selecting switch thereof, a portion of the lamp socket being shown in elevation, some of the wires extending between the switch and the current source and transformer being omitted, the means for retaining contacts 29 and 30 on switch plate 26 and for guiding them normal thereto being omitted.

Fig. 3 is a wiring diagram of the light or lighting device.

In its illustrated embodiment the lighting device of the invention has a base enclosure 10, shown in the form of a miniature barrel, centrally of the upper end or; lid of which there is afiixed an upstanding tube 11 forming a lamp socket supporting member or column. Screwed onto tube 11 and thus non-rotatably held thereby when in operative position is a shade-holder, the base portion of which is shown at 12. The shadeholder has wings struck out on each side to provide sockets for the lower ends 14 of a shade-holder loop, the remainder of which is not shown.

As more clearly shown in Fig. 2, there is a voltageselecting switch, generally designated 15, supported on the upper end of tube 11. Such switch includes an exposed annular, externally knurled switch-operating knob 16, which rotates coaxially of tube 11. Aflixed to knob 16 is an upper plate 26 on which is centrally screwed an upstanding short nipple 17, on the upper end of which there is secured a lamp socket 19 adapted to receive a conventional lamp bulb 20. As will appear, the structure of switch 15 is such that, as the knob 16 there of is rotated to the proper position to select the desired voltage at which lamp 20 is to operate, or to shut off the lamp bulb, the socket 19 and lamp 20 rotate with it. As noted, the shade-holder and the shade supported thereby are held from rotation.

Within the base enclosure 10 there is an autotransformer 21 which, through switch 15, supplies current at the desired voltage to wires 22 and 24 connected to socket 19. As is apparent in Figs. 1 and 3, the input terminals of autotransformer 21 are connected to a conventional current source L L The autotransformer shown has three output taps 32, 34, and 35 at intervals along its winding. The switch 15 permits the socket 19 selectively to be connected with successive taps, to be connected to the current source L L directly, or to be disconnected from the current source. The switch 15, when turned to oil position both disconnects the socket from the current source and from the autotransformer.

In the embodiment shown, the switch also deenergizes the autotransformer both when the socket 19 is directly connected to the current source and when the switch 15 is in olf position. As a consequence, no magnetic losses occur in the light when the lamp socket is con nected in either the full on position (D in Fig. 3) or the oil position.

The switch 15 shown includes a bottom plate 25, made of strong rigid electrically insulating material, such as molded plastic resin material, screwed onto the top of tube 11. Confronting the upper surface of lower switch plate 25 and spacedtherefrom is a parallel upper switch plate 26, also made of strong rigid electrically insulating material. As above noted, the lower end of nipple 17 is screwed centrally into plate 26. The switch-operating knob 16 is in the form of an annular member made of strong rigid electrically insulating material, and rotatably connects plates 25 and 26 of switch 15. As shown, knob 16 has a lower, radially inwardly projecting flange which fits within an annular peripheral seat on the lower surface of plate 25. The resulting bottom hub on plate 25 is received in the shallow bore formed by the inner cylindrical edge of the aforesaid flange on member 16. The knob 16 is thus accurately "guided for rotation on plate 25.

Plate 26 is secured to the upper inner edge of knob 16 by being screwed thereinto, as shown in Fig. 2, the plate being held from rotation with respect to the knob by one or more (one shown) locking studs 27 acting as keys spanning the threaded interface between plate 26 and the inner side wall of knob 16. Plate'26 is held in the position shown in'Fig. 2 wherein it is spaced from the upper surface of plate 25 by spring pressed contact 29 (designated hereafter the first contact) and another similar spring pressed contact 30 (designated hereafter the fifth contact), which are mounted on plate 26 and which are constantly thrust downwardly to engage either contacts on the upper surface of plate 25 or the upper surface of plate 25 itself between the contacts which it mounts. The means for retaining contact 2 9' and the similar contact 30 on plate 26, and 'for guiding them to the plate are omitted from 2 for clarity of illustration.

' The manner in which the supply circuit, including switch 15, operates will be more clearlyapparent upon consideration of 3. The switch, which for simplicity is there illustrated diagrammatically on an enlarged scale and is superimposed on the autotransformer, is shown with its contacts 29 and 30 in such position (position A) that lamp 20 is energized with the lowest voltage. Contacts 29 and 30 are permanently connected to wires 22 and 24, respec tively, leading to socket 19 mounting lamp 20.

Equally spaced on plate 25 of switch 15 along a portion of a circle at the right in Fig. 3 is a set 31 of second contacts a, b, c, and d, connected, respectively, to tap lead wires 32, 34 and 35 from the winding of the autotransformer, and to the upper terminal lead wire 36 thereof. Contact d is connected to side L of the current source by wire 37. Positioned on plate 25 diammetrically opposite the respective second contacts, and located on a portion of the same circle as the second contacts, are contacts a. b, c and d forming a set 39 of three contacts. The third contacts are connected to each other by a wire designated 41, and are connected to side L of the current source by wire 42. Located on plate 25 along a portion of a smaller circle is a set 40 of fourth contacts a", b", and c", which are radially aligned with contacts a, b, and respectively. The fourth contacts are connected together by a wire 44, and are connected to the lower terminal of the winding of the autotransformer by wire 45.

As shown in Figs. 2 and 3, each of the contacts 29 and 30 on plate 26 of switch has a double-winged flexible leaf contactor member disposed transversely to a central plunger stem. Such contactor member is non-rotatably held (by means not shown) with respect to plate 26, and it and its plunger are constantlyurged downwardly by a spring. The lower end of the plunger, which projects beyond the leaf contactor member, is rounded and func tions as a spring pressed detent which is selectively received in any one of a number of rounded shallow clepressions 47, which are in radial alignment with and positioned radially inward of, the respective ones of the second and third contacts. Generally midway between contacts a andd and contacts a and d are two additional shallow depressions 47"located at the off position on the same circle as depressions 47. The detent plungers of the contacts 29 and 30 cooperate with depressions 47 and 47 to hold the knob 16 and plate 26 of switch 15 stably in any selected one of its five possible positions, that is, the off position, and four positions (A, B, C, and D) of difierent light intensity emitted by bulb 20.

In each of positions A, B, and C-,'the contact 30 bridges the respective contacts a a", 12 ,5", c, 0'', thereby to energize the autotransformer by way ofL and wires 42, 41, 44, and 45. The voltage delivered to lamp 20, and thus the light intensity emitted by the lamp, increase in steps as switch 15- is successively rotated into positions B and C, since increasingly greater numbers of turns of the winding of the autotransformer are-employed.

In position D of the switch 15 the lamp 20 is fed directly from L wire 42, contact 30, and wire 24 and from L wire 37, contact 29', and wire 22, and, as noted, the autotransformer is deenergized since there is no fourth contact corresponding to the third contact d.

The structure of the switch 15 is such that knob 16 and thus plate 26 may be turned in either direction through as many revolutions or partial revolutions as desired. Since contacts 29 and 30 are identical, and since they are connected in the same manner to their respective lead wires 22 and 24, the switch functions in the samemanner as that described when knob 16 is turned so as to cause contact 29 to lie at the left in Fig. 3, to cooperate with the third contacts a, etc., and fourth contacts 0'', etc., and to cause contact 30 to lie at the right to cooperate with contacts a, etc. The off position of the switch is preferably located as shown, so that the lamp may either be immediately turned on to its full intensity by turning the switch knob clockwise to position D, or may be immediately turned on to its lowest intensity by turning the switch knob counterclockwise to position A.

Whereas for purposes of illustration I have shown and described a preferred embodiment of variable intensity electric light of my invention, it will be understood that such embodiment is illustrtive only, and that the invention is capable of numerous variations as to details. The scope of the invention, therefore, is to be defined by the claims appended hereto.

What I claim and desire to secure by Letters Patent 1s:

1. An electric light comprising an enclosure, an autotransformer contained in said enclosure, said auto-transformer having two supply terminals and a series of taps delivering different voltages, a lamp-supporting member projecting from the enclosure, and switch means for connecting the lamp to difierent taps of the auto-transformer, a source of current, two lead wires from the source of current, a first supply terminal of the auto-transformer being connected to a first lead wire, the switch means having a movable switching member with a first contact connected to one side of the lamp, a set of second, fixed, spaced contacts connected to the respective taps of the auto-transformer and selectively co-operating with the first contact at each on position of the switching member, and circuit providing means connecting the second supply terminal of the auto-transformer and the second side of the lamp to the second lead wire in a plurality of on positions of the switching element, said circuitproviding means includes a set of fixed interconnected spaced third contacts connected to the second lead wire, a set of fixed interconnected spaced fourth contacts connected to the second supply terminal of the auto-trans former, certain of the third contacts being positioned close to respective related fourth contacts, and a fifth contact mounted on the switching member, said fifth contact being connected to the second .side .of the lamp and bridging and connecting related third and fourth contacts when the switching member is in any one of a number of on positions there being one excess third contact as compared to the number of fourth contacts, and the contacts being so arranged and constructed that when the fifth contact cooperates with the excess one of the third contacts it disconnects the second terminal of the auto-transformer from the second lead wire, the switching member being annular and rotatably mounted around the lamp-supporting member, the first and fifth contacts being generally diametrically oppositely located on the switching member, the sets of third and fourth contacts being disposed on the lamp-supporting member in portions of concentric circles on one side of the lampsupportingmember, related ones of the third and fourth contacts being located generally on the'same radial line,

and the second contacts being disposed on the enclosure in a portion of a circle on the opposite side of the lampsupporting member.

2. An electric light according to claim 1, in which the sets of second, third and fourth contacts are so arranged that the ends of the second set of contacts are substantially spaced from the ends of the sets of third and fourth contacts, so as to provide an oil position for the switching member.

3. An electric light comprising an enclosure, a transformer contained in said enclosure and having a pair of input leads and a plurality of output leads supplying a plurality of different output voltages, a lamp socket mounted on said enclosure and adapted to receive a lamp, said socket having two contacts, an electric supply cord having two conductors extending out from said enclosure and adapted to be connected to a supply of alternating current, switching means comprising a plurality of contacts and a rotary switching member and means selectively connecting said switch contacts with said transformer input and output leads, said socket contacts and said supply conductors, said switching member being selectively rotatable between a plurality of on positions in which said transformer input leads are connected to said supply conductors and said lamp socket contacts are connected to different pairs of said transformer output leads to supply to said socket a difierent voltage in each of said positions, a further on position in which said pocket contacts are directly connected respectively to said supply conductors and said transformer is disconnected from said supply conductors and from said socket contacts and an off position in which said socket and said transformer are disconnected from said supply conductors.

4. An electric light comprising an enclosure, an autotransformer contained in said enclosure and having a pair of input leads and a plurality of output taps supplying different output voltages, a lamp socket mounted on said enclosure and having two lamp contacts, an electric supply cord having two conductors extending from said enclosure and adapted to be connected to an alternating current supply line, switching means comprising a rotary switching member, a plurality of fixed contacts arranged around the axis of rotation of said switching member and two movable contacts carried by said switching member and engaging selectively said fixed contacts, means connecting said movable switch contacts respectively with socket contacts, means connecting selected ones of a first series of said fixed contacts respectively with said transformer output taps, means connecting a second series of fixed contacts with one input lead of said transformer, means connecting a third series of fixed contacts with one of said supply conductors and means connecting a terminal contact of said first series and the second input lead of said transformer with the second supply conductor, said switching member being rotatable between a series of on positions in each of which a first movable contact connects fixed contacts of said second and third series to connect said auto-transformer input leads across said supply conductors and to connect one of said leads with one lamp socket contact while the second movable contact engages a contact of said first series to connect the other of said socket contacts with a selected one of said transformer taps to supply a selected voltage substantially less than supply line voltage, a further on" position in which said first movable contact engages only a contact of said third series to connect one socket contact to one supply conductor while the second movable contact engages said terminal contact of said first series to connect the other socket contact with the other supply conductor, the transformer being disconnected from said supply and from said socket, and an off position in which said movable contacts are disengaged from said fixed contacts.

References Cited in the file of this patent UNITED STATES PATENTS 390,911 Shallenberger Oct. 9, 1888 489,526 Doubleday Jan. 10, 1893 2,048,577 Thornton July 21, 1936 FOREIGN PATENTS 337,350 Italy Mar. 3, 1936 355,949 Italy Jan. 21, 1938 

